This section introduces aspects that may be helpful to facilitating a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is in the prior art or what is not in the prior art.
Metropolitan networks that use electronic packet and circuit switches for aggregation of data into optical wavelengths are inefficient due to the electronic processing of through-traffic that is not added or dropped at a node. Optical packet networks enable sub-wavelength optical bypass so that through-traffic does not consume network interface bandwidth and electronic-switch resources. The advent of coherent transmission with polarization division multiplexing (PDM) has improved the spectral efficiency of wavelength division multiplexed optical transport.